激光定向能量沉积IN718/316L异质金属结构界面组织及力学性能研究  

Research on Interfacial Microstructure and Mechanical Properties of In718/316L Bimetal Structure Manufactured by Laser Directed Energy Deposition

作　　者：徐刚 罗开玉[2] 鲁金忠[2] XU Gang;LUO Kaiyu;LU Jinzhong(School of Mechanical Engineering,Jiangsu University of Science and Technology,Zhenjiang 212100;School of Mechanical Engineering,Jiangsu University,Zhenjiang 212013)

机构地区：[1]江苏科技大学机械工程学院,镇江212100 [2]江苏大学机械工程学院,镇江212013

出　　处：《机械工程学报》2024年第1期179-189,共11页Journal of Mechanical Engineering

基　　金：国家重点研发计划(2022YFB4600504);江苏省重点研发计划(产业前瞻与关键核心技术)(BE2022069-4);江苏省六大人才高峰(2019-GDZB-251)资助项目。

摘　　要：针对IN718镍基合金和316L不锈钢异质金属连接形成的明显界面导致构件整体强度低的问题,采用激光定向能量沉积(Laser directed energy deposition, LDED)工艺制备了IN718和316L直接连接和梯度连接构件。采用扫描电子显微镜(Scanning electronmicroscope,SEM)和电子背散射衍射(Electron backscattered diffraction,EBSD)观测了异质金属直接连接和梯度连接构件的界面处微观组织分布。此外,采用数字图像相关法(Digital image correlation, DIC)原位拉伸技术研究了IN718/316L异质金属直接连接和梯度连接构件的整体强度,以及拉伸过程中界面处的应变规律。结果表明,IN718/316L直接连接构件存在明显界面,界面处微观组织分布存在较大差异;从IN718端至316L端,Fe等元素含量明显升高, Ni和Nb等元素含量明显降低。IN718/316L梯度连接构件无明显的连接界面,沿梯度方向,微观组织由胞状晶向柱状树枝晶转变。抗拉强度与直接连接构件相比提高了约28.77%。采用异质金属梯度连接可有效消除异质金属间的明显界面,实现元素分布渐变,明显提升异质金属的抗拉强度。Aiming at low strength due to the obvious interface formed by the connection of IN718 and 316L,the direct and gradient connected IN718/316L components are manufactured by laser directed energy deposition(LDED)process.Scanning electron microscope(SEM)and electron backscattered diffraction(EBSD)are used to observe the microstructure at the interface of directly and gradient connected heterogeneous metals.In addition,the digital image correlation(DIC)in situ tensile technology is used to investigate the overall strength of directly connected and gradient connected IN718/316L components,as well as the strain distribution at the interface during the tensile process.The results show that there is an obvious interface between directly connected IN718/316L components,and the microstructure of 316L and IN718 regions near the interface is quite different.Elements like Fe are significantly increased at the interface,while elements including Ni and Nb are significantly decreased from the IN718 to 316L region.There is no obvious interface in gradient connected IN718/316L,and the there is a trend of transformation from cellular crystal to columnar dendrite in microstructure along the graded direction from pure 316L to pure IN718.In addition,the tensile strength of gradient connected IN718/316L is increased by 28.77%compared with that of direct connection method.The elimination of obvious interface between heterogeneous metals,the gradual element distribution and significant improvement of the tensile strength are realized by the gradient connecting of heterogeneous metals.

关 键 词：激光定向能量沉积 IN718/316L 功能梯度材料 拉伸性能 显微组织 

分 类 号：TG156[金属学及工艺—热处理]